Precision alignment of optical arrays to ribbon fiber can be difficult. In order to minimize loss in multimode fiber, a placement tolerance of +/xe2x88x925 xcexcm (micrometers) is needed. In contrast, the 3 standard deviation alignment tolerances of single-mode optical fiber is less than 1 micron. To achieve this alignment tolerance, active alignment and complex vision systems are often used. This alignment requirement reduces manufacturing output and yield, making optical assemblies more costly than traditional electronic packaging techniques.
Active alignment uses the features of optical components to align optical fibers to an optoelectronic device. For example, in coupling an optical fiber to the surface of a light emitting laser, a device such as a photodetector is used in alignment. The photodetector is positioned at one end of the optical fiber, detecting the light from the surface emitting laser at the other end of the optical fiber. The optical fiber""s position, relative to the surface emitting laser, is adjusted until light hitting the photodetector reaches a maximum. When the photodetector senses a maximum amount of light, the fiber is bonded in a permanent position. Increased manufacturing demands have caused a need for replacement of this type of alignment, as it can be time consuming and costly.
Electronic packaging assemblers often use pick-and-place methodology to position electronic components for subsequent assembly. Components are picked from a component holder and placed on a substrate no more than 25 microns from an absolute reference position. This alignment tolerance is 5 times greater than that required for low-loss optical interconnects.
Thus, there is a need for high precision alignment and placement of optical components. Described herein is a detailed methodology for accurately aligning optical components to one another, using features applied to the optical components.
A method and apparatus are provided for aligning an array of optical devices with optical processing equipment. The method includes the steps of providing a transparent substrate with a plurality of optical transmission paths passing directly through the substrate, providing a plurality of alignment guides on the optical array, providing a complementary plurality of respective alignment guides on the transparent substrate and guiding the optical devices of the array into alignment with the substrate using respective pairs of the alignment guides on the optical array and transparent substrate.